It can also be substituted with precise hf generator, accurate frequency meter and hf signal meter. I used NWT7 v2.1, you can use any amateur or professional wobbluscope. The measured RS-3017X resonators had Cp=5.8pF.ģ) Measuring crystal parameters using 3dB method. You should measure couple of resonators from entire set and calculate average value. We can assume Cp= 4pF if we don’t have C meter. To measure Cp, C meter with 10pF range is needed. Not all filter design programs allows to insert Cp value. It is not necessary to measure Cp, but it allows to compute filter elements more accurately. Small plastic box, in which crystals were delivered, was very helpful. It is important to not mix the crystals after measurements. When using wobbluscope, we can also measure all crystal parameters using 3dB method. ![]() To measure fs we can use wobbluscope ( fs is a maximum signal frequency) or simple oscillator and frequency meter with resolution at least 10Hz. In general allowed difference between crystals fs is +/-2% of designed filter bandwidth. – crystals for CW filter should be selected to have fs +/- 10Hz Measurement examples are for custom ordered resonators 8214 i 8215kHz (RS-3017X) made by polish company Omig.ġ) Selecting crystals based on series resonance frequency ( fs) ![]() ![]() Values of crystal parameters needs to be determined to correctly design crystal ladder filter.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |